Saliva test spots hearing loss virus in newborns

A saliva test has shown to be much more effective in screening for Cytomegalovirus in newborns than the traditional test, a study shows.

Cytomegalovirus (CMV) is a virus which causes hearing loss in at least 10-15 % of infected newborns. The virus is passed from mother to foetus during pregnancy. So far, there is no accurate test to determine the virus and there is still no cure. Today, the traditional heel stick blood test is used to test newborns, but the method is not particular effective, as it misses 60-70% of cases.

"Most babies infected with CMV don't show symptoms at birth," said James F. Battey, Jr., M.D., Ph.D., director of the NIDCD (National Institute on Deafness and Other Communication Disorders, USA). "It is important for us to develop diagnostic tools to screen babies for congenital CMV infection so that those who test positive can be monitored for possible hearing loss and, if it occurs, provided with appropriate intervention as soon as possible."

A study conducted by researchers at the University of Alabama at Birmingham found that a saliva test in newborns can detect almost all cases of the virus. In order to perform a saliva test one need's to examine saliva swabbed from the baby's mouth.

One-day-old babies

During the study, the researchers examined mouth swabs taken from almost 35,000 infants from seven U.S. hospitals. They were taken when the babies were about a day old.

The researchers tested the samples and confirmed their results. For this they used a testing procedure that is precise, but too unwieldy for widespread screening use. They found that the Saliva test correctly detected the virus in 97-100% of the cases, depending on whether the samples were dried or liquid.

It can be done

"We now know that we have a test with saliva that works," study co-author Dr. Suresh Boppana said in a news release from the National Institute on Deafness and Other Communication Disorders. "The challenge is, unlike the dried blood spot [heel stick], which is already used for newborn screening in hospitals across the country, that we don't have a system in place for the collection of saliva. But we have shown that if you wanted to test a lot of babies for congenital CMV infection, it can be done."

In the future, the researchers want to find out how much congenital CMV infection contributes to overall hearing loss at birth and between the ages of 3½-4 years old.